\documentclass[tikz]{standalone}
\usepackage{amsmath,amssymb}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{xcolor}
\usepackage{tkz-euclide,tkz-fct}
\usetikzlibrary{arrows.meta, bending, patterns.meta, hobby, ducks}
\usetikzlibrary{shapes, backgrounds, decorations.pathmorphing, calc}
\begin{document}
\begin{tikzpicture}
\edef\xmin{-5.000000}\edef\xmax{5.000000}
\edef\ymin{-5.000000}\edef\ymax{5.000000}
\edef\xstep{1.000000}\edef\ystep{1.000000}
\tkzInit[xmin=\xmin, ymin=\ymin, xmax=\xmax, ymax=\ymax, xstep=\xstep, ystep=\ystep]
\tkzClip


% POINT DEFINTIONS
\tkzDefPoint(-2.285491419656786, 3.12792511700468){A}
\node[draw=black, fill=black, rectangle, minimum size=3, inner sep=4, rounded corners=3.0pt] (A) at (A) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 1}\\[0.2cm]This is the first node.
}
}};
\tkzDefPoint(-2.5195007800312013, -2.6287051482059285){B}
\node[draw=black, fill=black, circle, minimum size=3, inner sep=2] (B) at (B) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 2}\\[0.2cm]This is the second node.
}
}};
\tkzDefPoint(2.566302652106084, -1.4430577223088923){C}
\node[draw=black, fill=black, diamond, minimum size=3, inner sep=2] (C) at (C) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 3}\\[0.2cm]This is the third node.
}
}};

% DRAW SEGMENTS
\draw[line width=0.8, -{Stealth[scale=1.5]}, draw=black](A) -- (B);
\draw[line width=0.8, {Latex[scale=2.0, round]}-{Latex[scale=2.0, round]}, dashed, draw=black](B) -- (C);
\draw[line width=0.8, {Stealth[scale=1.5, open]}-, draw=black](C) -- (A);

\node[draw=black, fill=black, rectangle, minimum size=3, inner sep=4, rounded corners=3.0pt] (A) at (A) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 1}\\[0.2cm]This is the first node.
}
}};
\node[draw=black, fill=black, circle, minimum size=3, inner sep=2] (B) at (B) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 2}\\[0.2cm]This is the second node.
}
}};
\node[draw=black, fill=black, diamond, minimum size=3, inner sep=2] (C) at (C) {\parbox{2cm}{
\textcolor{white}{
\textbf{Test 3}\\[0.2cm]This is the third node.
}
}};

% POINT LABELS



\end{tikzpicture}
\end{document}
